The present invention relates to novel alkyl phosphates having a branched alkyl group, which are useful as surfactants, lubricants, dispersants, emulsifiers, additives, stabilizers, solubilizers, water-repellants, antistatic agents and the like.
Hitherto, trialkyl phosphate compounds have been widely used as additives such as plastisizers and stabilizers, lubricants, dispersants or the like. Most of trialkyl phosphate compounds used as plastisizers are higher alkyl phosphates in view of volatility and water-solubility of the compounds. Typical examples of such alkyl phosphates include trioctyl phosphate, tributoxyethyl phosphate, triphenyl phosphate and octyldiphenyl phosphate. Triaryl phosphates are more advantageous as plastisizers, but they have a problem of low-temperature resistance.
Dialkyl phosphates and monoalkyl phosphates are generally used as surfactants. The alkyl phosphate surfactants are used, for instance, as wetting agents such as disclosed in R. Oda et al., "Surfactants and Applications thereof", Maki Shoten, p98, (1957), collecting property improving agents for fibers such as disclosed in Japanese Patent Application Laying-open (KOKAI) (referred to as "J.P. KOKAI" hereinafter) No. Sho 47 39788, antistatic agents such as disclosed in Japanese Patent Publication (KOKOKU) No. Sho 42-11480 and softening agents. Alkyl phosphates having a branched alkyl group, in particular, are known to be useful as lubricants for treating fibers such as disclosed in J.P. (KOKAI) No. Sho 48-19892.
While various alkyl phosphate compounds have been developed and practically used as described above, it is still sought to improve the various properties of the alkyl phosphates.
On the other hand, it has been known that cell membranes of archaebacteria are composed of glycerolipids having a hydrophobic group comprising linear isoprenoids bonded with ether bonds. Recently, in investigations of the functions of cell membranes of archaebacteria and application thereof for liposomes, reported was synthesized glycerophospholipids having isoprenoid side chains, which imitate the lipids constituting the cell membranes of archaebacteria (Yamauchi et al., J. Am. Chem. Soc., 112, p3188 (1990); Toda et al., Preprints for Spring Conference (1990) of the Chemical Society of Japan, p1793). As a result of these investigations, it was found that these glycerophospholipids having isoprenoid side chains have a low phase transition point and that the lipid bilayer membrane constituted by the glucerophospholipids has an excellent barrier property.
Further, also known were lipid bilayer membranes and lipid-bilayer-membrane-immobilized polymer films utilizing quaternary ammonium salts having isoprenoid chains as disclosed in J.P. (KOKAI) No. Hei 2-288849 and it was found that those lipid bilayer membranes have fluidity similar to that of biological membranes as well as excellent flexibility and strength. However, any alkyl phosphate having isoprenoid side chains, which may be suitably used as surfactants and dispersants, is not reported.